Leveraging recovery effect to reduce electromigration degradation in power/ground TSV

Abstract

With increasing temperature and current density, electromigration (EM) becomes a major interconnect reliability challenge in power distribution networks (PDNs) of three-dimensional integrated-circuits (3D ICs). In order to improve the EM reliability of power/ground (P/G) through-silicon-vias (TSVs), the conventional solution is to use larger TSVs in order to decrease the current densities. In this work we exploit the recovery effects for EM reliability improvement by periodically deactivating P/G TSVs. In order to predict EM-related lifetime for TSV accurately, a novel three-phase EM model is proposed with a focus on single damascene via-last process. Different from existing TSV EM models, the new TSV EM model considers the nucleation phase and the impacts of initial thermo-mechanical stress, which is significant for the TSVs in addition to this recovery effect modeling. Furthermore, a recovery-aware repair architecture is developed for EM reliability improvement. Applied to 3D benchmark designs, the proposed repair approach increases EM-related lifetime of the P/G TSV grid by 4.4X in average relative to the conventional TSV sizing method, with negligible area overhead.